Optimized GTS Utilization for IEEE 802.15.4 Standard

Low rate and low processing wireless applications are under high demands since last decade. Most of these applications use IEEE 802.15.4 standard on their physical and Medium Access Control (MAC) layers. The standard operates in 868MHz, 915MHz, and 2400MHz frequency bands, and offers superframe structure in its beacon enabled modes. This superframe structure comprises of Contention Access Period (CAP) and Contention Free Periods (CFP). During CFP, nodes are allocated Guaranteed Time Slots (GTS) to transfer their data. In this work, CFP slots of superframe structure have been fine-tuned for better link utilization. A knapsack optimization algorithm is designed to accommodate more CFP requesting nodes. The proposed scheme improves the link utilization and accommodates more nodes as compared to the existing standard. The analytical results show that our proposed work improves the link utilization almost 50% and allows up to double of nodes as compared to the standard on all three frequency bands.